clk: renesas: r8a7795: Add USB-DMAC ch3 clock

This patch supports the clock of USB-DMAC ch3 module added from R8A7795
ES2.0 SoC.

Signed-off-by: Takeshi Kihara <takeshi.kihara.df@renesas.com>
Signed-off-by: Yoshihiro Kaneko <ykaneko0929@gmail.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>